In 1942, for the first time, the life of a patient was saved by treatment with penicillin. Yet, the battle against infectious diseases and pathogenic bacteria continues. In 2006, the Infectious Disease Society of America reported that each year, 90,000 of the 2 million people who acquire a hospital bacterial infection will die. That is a 4.5% mortality rate resulting from just visiting a hospital. Multi-drug resistance bacterial strains are a major problem and one that has been increasing very rapidly every year during the last few decades. Beside the need for new antibiotics, there is also a need to quickly identify and quantify a bacterial infection in order to embank the spread of the infection into an epidemic.
In the food industry, pasteurization involves heating liquid food products like milk, juices, etc. to kill pathogenic organisms such as viruses, bacteria, molds, and yeast. However, some amount of microbes may survive the pasteurization process or may be inadvertently introduced during further processing. Such microbes typically cause spoilage of food products causing an economic loss exceeding $1 billion each year. Moreover, if the surviving microbes are pathogenic, outbreaks of food borne illnesses may occur among consumers. It has been estimated that approximately 76 million food borne illnesses occur per year in the U.S. alone, of which up to 5000 cases result in death, thereby affecting the economic loss even further.
Therefore, detecting and quantifying microbes that survive treatments such as pasteurization is important for assuring food quality and food safety and further for complying with standards set by government agencies or trade organizations. For example, the U.S. Pasteurized Milk Ordinance requires that “Grade A” pasteurized milk has a total microbial count of not more than 20,000 colony forming unit (CFU)/ml and a coliform count of not more than 10 CFU/ml. Food producers and/or market food distributors have to perform microbiological tests to fulfill the regulatory standards. It is important to their economic operation that they do so with the least possible expenditure of material and labor.
There are presently several ways to detect microbes in clinical or food samples. Broadly categorized, there are (i) traditional methods such as plate cultures and biochemical assays, (ii) DNA and antibody based methods, often involving micro/nano particles and fluorescence, and (iii) other “automated” techniques that rely on monitoring the effects of bacterial metabolism on the medium. Of these, traditional methods are the most extensively used, and often serve as the standard to which other techniques are compared. However, such traditional methods are tedious, labor intensive, and require very long times to detect microbes, which can range from overnight to weeks depending on the type of the organism and medium used.
The foregoing are solely two examples how microbes affect people's daily life and the economy. It is well known how widespread the impact of such microbes is, spanning from the health care and pharmaceutical sectors, over the food and livestock sectors, into municipal and rural population, even into the oil and gas industries, and industries served with pipelines or storage tanks are corroded by microorganisms present. Therefore, in a broad area of economic fields, there is a need to provide an improved method and device to detect, identify, quantify, viable microbes in a sample.